Controlling accessibility between multiple data centers can present challenges. Some existing techniques such as ADV-RTR (router advertisement messages), ISID (service identifiers), and route-map constructs may require burdensome configuration and numerous host entries programmed into data paths. For example, a backbone route map may accept all routes for specified Level 3 (L3) ISIDs from all domains. Consequently, a large number of ADV-RTR and ISID based accept policies may be needed if routes need to be accepted from only one or a few data centers from among the data centers that share a same set of L3 ISIDs.
Embodiments were conceived in light of the above mentioned needs, problems and/or limitations, among other things.